3 concepts
Phylum Echinodermata
Echinoderms are invertebrates that have pentaradial symmetry, a spiny skin, a water vascular system, and a simple nervous system.
Classes of Echinoderms
Echinoderms consist of five distinct classes: sea stars, sea cucumbers, sea urchins and sand dollars, brittle stars, and sea lillies.
Phylum Chordata
The phylum Chordata contains all animals that have a dorsal notochord at some stage of development; in most cases, this is the backbone.